I'm looking to ad a mixer in the near future to my station. As I peruse many of the Pro Audio sites I see there are different types of mixers. Specifically, there are non-powered, powered and USB Mixers. I'm not asking for advice on which one to buy, I'm just trying to understand the terminology. My station consists of a MXL-990 Condenser mic, Behringer MIC200 Preamp (which I hope to replace with the mixer) to a Kenwood TS-570SG. Thanks for your help!